What is the "data-sigil" HTML attribute?

I just came across a website that has "data-sigil" as an attribute for HTML elements like a, div, label, abbr.

I开发者_JAVA技巧t accepts a string value, like this:

<a class="a1class" href="/more.php" data-sigil="some-description">More</a>

Googling "data-sigil" HTML attribute yielded only a mailing list posting which doesn't seem to explain much in the context of an HTML attribute.

Any idea what that mysterious "data-sigil" HTML attribute could be?

It's actually a sigil from Javelin (Facebook JavaScript framework). Javelin separates style markers (ids and classes) from functional markers. They use sigils for the latter. See:

http://phabricator.com/docs/javelin/article/Concepts:_Sigils_and_Metadata.html

Any attribute starting with data- is an HTML 5 data- attribute.